Inventor. He will be remembered as the inventor, improver of the steam-engine. This resulted from his improvements to Thomas Newcomen's steam-engine by inventing a separate condenser. He perfected a rotary engine and defined one horse power as the rate at which work is done when 33,0001bs are raised one foot in one minute. The electrical unit of power, the "watt", was named after him. Besides being an inventor and mechanical engineer, he was also a civil engineer and made various surveys of canal routes. (bio by: s.canning)